Many safes and security containers have high security combination locks installed thereon. The locks on the cabinet or container are subject to many types of attack in an effort to open the lock. Attacks may range from destruction of the lock itself, an attack such that the operator cannot detect that the lock has been attacked, violated or compromised, and further to an attack such that an expert cannot detect that the lock has been violated or compromised.
For a high security lock to be used for the highest level of protection such as that used for the most sensitive documents, United States government standards require that a lock be approved under Federal Specification FF-L-2740. The lock must be able to withstand attack for a period of thirty minutes; additionally, any access through such a lock must not be detectable by the operator. The type of attack and entry which is undetectable to the operator is known as a covert entry. Covert entry and covert attack are particularly pernicious since the authorized operator does not know that the contents of the safe or security container have been compromised. By virtue of the fact that the lock appears to have not been violated or tampered with but which in fact have been compromised, National security secrets which are believed to be secure thereafter may be relied upon in the normal course of governmental business; the results of such reliance on secrets which have been compromised without the knowledge of the custodian of those secrets can be particularly ruinous.
A great deal of effort has gone into the design of locks, containers and other devices which will resist covert attack and covert entry. The most efficient way to reset covert attack or entry is to design the lock so that the operator must be able to observe and recognize signs which indicate any type of attack. The obvious observable signs of a physical attack include disruptions in the surface of the security container, mars, scratches or other abuse indicators on the lock dial or lock housing.
A lock also should reveal its compromised status if a covert entry should occur. With the revelation that covert entry has occurred with respect to a lock and this covert entry having been recognized by the operator, the operator then is aware that the contents of the security container may have been compromised and thus take steps to insure that the damage occasioned by such compromise either is eliminated or minimized.
Since the covert entry standard for locks requires that to be a covert entry the entry be undetectable by the operator, no external markings, mars or other signs of attack can remain for observation; additionally, the lock must properly function after the attack or the operator then would be aware that the lock may have been compromised. A solution to the covert entry standard is to render the lock to a condition that the operator must observe and that will clearly indicate to the operator that a covert attack had occurred or that covert entry had been accomplished. This operator indication preferably must be shown in such a way that the entry will be unavoidably indicated. For example, after the covert entry the lock could be rendered inoperable until the lock is reconditioned for proper operation.
Although destruction or damage to the container renders the attack and entry readily observable, any person attempting a covert entry would avoid leaving such obvious indications. Therefore, with the lock remaining in undamaged, or unmarked condition, the detection of covert entry and the actions based thereon must detect any movement of the bolt to permit entry to the container or other attack which would not be otherwise observable. If the lock cannot be affected in a way that it is observable or detectable by the operator and the container must maintain the same structural integrity and appearance after the covert entry attack, the only ways for the covert entry to occur are to move the bolt from the locked or extended position to the unlocked or retracted position or to completely remove the bolt, thereby allowing the door of the container to be moved to permit access. Thereafter, the door or cover must be repositioned in the normal closed position and the fact that the door has been moved must not be observable or detected by the operator.
If the back cover is removed to tamper with the internal works of the lock, then the operator may not be able to observe any evidence that the back cover has been removed. The back cover removal may be considered a covert entry or covert attack.
With electronic high security locks there are opportunities to inform the operator that covert entry has occurred. Covert entry is considered any withdrawal of the bolt from its extended or locked position without the entry into the lock of an authorized combination, or the removal of the lock back plate thereby granting access to the electronics of the lock. Other forms of attack which may be considered covert attacks are lock housing cover removal or magnetic attack.